Abstract
BACKGROUND: Rapid Diagnostic Tests (RDT) have become an essential tool for the control of malaria worldwide. Their simplicity of use and their reliability make them ideal for the diagnosis of malaria in endemic areas. Numerous brands are now available on the market. In South East Asia, where both Plasmodium falciparum and Plasmodium vivax are prevalent, the Abbott-Bioline™ Malaria Ag Pf/Pv rapid diagnostic test (for the detection of Pf HRP2 and Pv LDH) is deployed widely but, after years of satisfactory performance, its recent sensitivity has been questioned after multiple false negative results were reported. METHODS AND RESULTS: The study was conducted between October 2024 and January 2025. A field comparison with the First Response(®) Malaria Ag pLDH/HRP2 RDT (for the detection of Pf HRP2 and Plasmodium Pan LDH) and microscopy (i.e. the gold standard) was conducted on the Thailand-Myanmar border where, until recent conflict, falciparum malaria was close to elimination. Overall (combining all field specimen), the Bioline RDT had a sensitivity of 0.18 and a specificity of 0.99 for P. falciparum. The corresponding figures for the First Response RDT were 0.89 and 0.93 respectively. For P. vivax malaria, the Bioline RDT had a sensitivity of 0.44 and a specificity of 0.99, while the First Response RDT had a sensitivity of 0.59 and a specificity of 0.98. In laboratory studies, using samples from patients or standard antigen panels (NIBSC antigens including histidine-rich protein 2 (HRP2 and P. vivax lactate dehydrogenase (PvLDH)), Bioline RDT consistently showed fainter result lines compared to the other brands of RDTs, at parasite densities between 208 and 1993/µL, and some tests had no visible lines at all. The Bioline RDT detected only 45.0% (9 of 20) cases of acute falciparum malaria and 74.0% (37 of 50) cases of acute vivax malaria whereas the First-response RDT, identified 90.3% (18 of 20) of P. falciparum and 84.0% (42 of 50) P. vivax cases. CONCLUSION: The Abbott-Bioline™ Malaria Ag Pf/Pv RDT that were obtained in 2024 failed to detect microscopically confirmed cases of malaria and is not fit for purpose. This test should no longer be used and should be replaced by one with adequate performance.